Questlove just suggested to our photog ... Jimmy Fallon's mom has either passed away or it's about to happen.
We got "The Tonight Show" band frontman leaving the Director's Guild in West Hollywood Saturday and asked him how Jimmy's doing after the family emergency that canceled taping of the show Friday -- his answer implies Fallon's lost someone close to him.
Reports out say Jimmy's mom is very ill in the hospital, so he left Friday to join his family and be with her.
Questlove tells our guy he's not sure when 'The Tonight Show' will begin taping again.
We reached out to Fallon's team ... no word back so far.